I have fitted my AR coated screen but it hasn't had the expected effect. When viewed in direct sunlight (doesn't happen that often here in England!!) the sunlight appears to be reflected by the glass VFD itself. This makes it difficult to see what's actually being displayed by the Empeg. Does anyone else have this problem? I'm wondering if a polarising filter behind the coloured screen would help. Any ideas anyone?
Oh... and last night my knob started slipping (fnar fnar) - I'll have to get on to Empeg to send me out a new one.
All in all though, a great product :-)

beaker
12 gig blue

My AR screen arrived last week and it works perfectly. Yes in direct sunlight it is washed out, but try to show me any kind of display screen that isn't.

Perhaps you got an old non AR screen?

John

Thanks for your reply.
No, it's definitely an AR screen, it's got a slightly rough surface to it which 'softens' the display. I had Empeg send one out to me. The only type of display which doesn't really suffer is LCD but I they're not really suitable for the fast moving graphics (discussed to death elsewhere on this bbs).

beaker
12 gig blue

I received a blue one and it really doesn't help any. I may end up putting the old one back on because I think it looks better in most conditions.

-Rob
-----
12GB MK2 Blue 090000736 (6166 in the queue)

In direct sunlight (i.e., the sun is shining directly upon the VFD display), I can only barely read the text. If yours is completely washed out (if you can't see any text at all), then your VFD might not be operating at its full brightness. If you can barely see the text in direct sunlight, then that's normal: It's the best they can do with the VFD and an AR panel.

___________
Tony Fabris

In normal ambient daylight here in England (alright so it's dark most of the time) the display is perfectly bright to see easily. However when the sun is low (which it is most of the time at the moment) and it is shining directly into the Empeg display the flourescent elements inside the VFD appear to reflect this light back out and therefore reduce their contrast with the elements which are emmiting light.
As light which is reflected is quite often polarised (but not always) I thought that this might be a cure. Anyone got any ideas, experience or comments on this idea?
It's not a great problem at the moment as the sun isn't out for long enough. I'm thinking ahead to the summer when the sun will be out for more than 10 seconds (ha ha!!) in any 24 hr period.

beaker
12 gig blue

Same here (green). Works better for me with the original non AR panel so I put this one back on. Tx J.

What are you going to do with your blue AR screen?
Would you maybe give it away? I'd be interested in having a different color...

TeeMcBee
Got my Mk2! # 080000143

What beaker said above about the elements of the VFD shining back is right on the mark. In direct sunlight, the non-lit elements shine just as bright as the lit elements. It's because the elements themselves are too reflective, reflecting sunlight back as if the element was lit. The best way to solve this problem is to find a VFD that is not reflective. Either that, or find a display screen that can distinquish between reflected light and light emitted by lit elements. I'm not surprised the AR screen still does not work that well in direct sunlight.

Hrm.. I got my red AR faceplate in.. it looks signifigantly better.. tho almost all displays that are backlit like the empeg loose something in sunlight.. the empeg looks better than most laptops in sunlight. :)

12gig red mk2 -- 080000125

I agree. My green display is better in direct sunlight than before. It's still not great, but that's hardly empeg's fault. I have a navigation system above the empeg, it's even indented a bit, and it suffers wash-out in direct sunlight. Good thing I don't have to worry about it all that much in my nice big van, though

DiGNAN

I agree the display itself would have to be AR coated to work effectively but that would it be very difficult at best to coat the VFD with a one-way mirror surface. While the AR coated screens don't really work as intended I like the effect they have from the dimpled surface it seems to give a blurred delayed look to the visuals.

#695 Mk2 BLUE 12Gig

Ask and I may tell you

...should be easy enough to test. You should be able to buy polarizing film, and just cut it to match the faceplate. Natural static should keep the film stuck to the faceplate, although if the VFD is warm, I don't know it the film will tolerate that.

Let us all know if you try that out.

- - - - - - - - - - - - - - - - - --
MK2 #141, green, 12GB

Yeah, I've looked for some kind of polarising film but haven't had much luck so far. Even though I did suggest this as a possible cure in the first place I'm not very confident about it actually working. I'm also not sure whether it would darken the actual display too much either. Still, I'd like to try it all the same. I'll let you all know if I find any polarising film and whether it helps at all.

beaker
12 gig blue

Silly suggestion on the direct sunlight bit, have you looked at polarizing film or tint for the offending windows? I know I've seen good & bad jobs of tint, but thought I'd throw it out there.

My take is that I don't really expect any display to work well in direct sunlight. I think the AR screen does what it's supposed to though.

-Zeke

just say you weren't paying much attention...

Interesting thought. Trouble is I'm not a "tinted windows" kinda guy though. Most of the cars around here with tinted windows are either driven by teenage boy racers (no offence to teenage boy racers) or drug dealers.
Thanx for your input anyway.

beaker
12 gig blue

Yeah. I know what you mean. I don't have them myself but I thought I toss that out there. Skinning cats & all.
I have dreams of an active LCD windshield that uses cameras to track the driver's eyes & black out oncoming headlights. We just need to build one & ditch the eyetracking for empeg tracking. Anyone? ;-)
Maybe by the time I'm 90. I'd probably put it into one of these: http://www.moller.com/skycar/m400/.

-Zeke

just say you weren't paying much attention...

I should say it would be difficult for the home user in general to coat the VFD per Empeg. But maybe Empeg could do it to the forthcoming units.
I'd hate to have the film melt to the VFD.

#695 Mk2 BLUE 12Gig

Ask and I may tell you

I also received my AR-coated screen (blue).
In the installation instructions there was notice of removing some protective skin off the screen before installing.
I've peeled for a quarter of an hour, but I couldn't get anything off. I just installed it...
Is there some protection-skin on the AR screens?

Frank van Gestel

I have dreams of an active LCD windshield that uses cameras to track the driver's eyes & black out oncoming headlights.

I thought I was the only one who had that idea. (Mine included blocking the sun, too.)

___________
Tony Fabris

Surely you don't want to completely block oncoming headlights? . They are partly to let you know about the oncoming car that's immediately behind the aforementioned oncoming headlights.

Otherwise, you could just put masking tape over your eyes, and you'd never have this problem again .


Roger - not necessarily speaking for empeg

No, the idea would be to use LCD to darken the excessive blinding glare while still allowing you to see what's behind the glare. It would actually improve your ability to see the oncoming cars because you wouldn't have to avert your eyes.

The only way it would work is if the LCD were dynamic and could localize to small regions of the window, and track depending on the driver's head position.

It's all a pipe dream, of course, such a system would be so prohibitively expensive as to only be available on fighter jets or something.

___________
Tony Fabris

Err, no, not on the current batch. Do the installation instructions say for Mk.1 or Mk.2? If Mk.1 then someone made a packing mistake, if Mk.2 I need to update the text!

Rob

I thought I was the only one who had that idea. (Mine included blocking the sun, too.)

Me too.

Steve Bates

We can dream though. At least until summer comes and I don't have to commute in total darkness.

-Z

just say you weren't paying much attention...

I'd probably put it into one of these: http://www.moller.com/skycar/m400/.

I don't want to rain on anybody's parade here, but just like that 78 million dollar personal submarine discussed in another thread, there are a lot of numbers that don't add up here.

1) Gross weight 2400 pounds; 900 miles @ 15 MPG = 60 gallons of fuel at 6.6 lbs per gallon = about 400 lbs for fuel. Four passengers at 185 lbs each = 740 lbs. Add another 60 lbs for oil, coolant, etc., and you are up to 1200 lbs useful load, leaving 1200 lbs for the empty aircraft. OK, no arguments there, just laying the groundwork.

2) Eight 120 horsepower engines in a vehicle that weighs (empty) 1200 pounds. Even assuming that the airframe were made of exotic unobtainium alloys and weighed only 800 pounds (impossible for a four-passenger vehicle) that leaves 50 pounds for each 120 HP engine, which is about 1/3 the weight per horsepower of any internal combustion engine I am aware of.

3) 960 horsepower... it would probably need that to generate the thrust to keep it in the air. Since the aiframe lacks wings or other lifting surfaces, the lift/drag ratio is going to be ridiculous. I don't believe that 960 HP would be enough to both provide lift and provide propulsion to a maximum speed of 390 MPH.

4) A general rule of thumb for fuel consumption in an internal combustion engine lightweight enough to be used in an aircraft is one-half pound of fuel per horsepower hour. Figure 75% of max power at the claimed cruise speed of 350 MPH, that would be 720 HP, which would require 360 lbs of fuel per hour or 54 gallons of fuel per hour, which works out to something less than 6.5 miles per gallon, about 40% of the mileage they are claiming. Their FAQ page strongly implies that the engines are Wankel-type rotary engines. These engines have never been known for fuel economy.

5) Operating ceiling of 30,000 feet. By the time they reach that altitude, they might have 400 horsepower left (internal combustion engines don't work well at Mt. Everest altitudes) and remember, there are no lifting surfaces on this little jewel, so it's all thrust. Some really good mountain rescue helicopters (priced in the multi-million dollar range) with big honkin' twin turbojet engines putting out several thousand shaft horsepower at sea level (and without as large a power penalty at altitude as an internal combustion engine) can make it up to about 23,000 feet, and that's with several hundred square feet of lifting surface (rotors) spinning at 1,000 RPM or so.

6) Noise level: 65 decibels at 500 feet. Yeah, right. With eight engines cranking out 960 horsepower and four eight-bladed ducted fans screaming for all they're worth... 65 decibels is the noise level you would expect to hear in a good luxury car at 60 miles per hour. You wouldn't even need to crank your empeg into overdrive to overcome that much noise.

7) Maximum rate of climb 7800 feet per minute. That's the equivalent of 90 miles per hour straight up. A good twin-engine turboprop aircraft with double the power plus the considerable advantage of generating lift by means of wings (far more efficient than brute thrust) might be able to attain a third of that rate per climb.

8) 900 mile range. I don't see how. With no aerodynamic lift, the fuel efficiency (i.e., miles per gallon) could only improve as speed went up (at hover, you are getting zero miles per gallon) but somewhere along the line the fuel consumption curve will butt heads with the wind drag curve and that's likely to be in the neighborhood of 100 MPH. (just guessing here, but to push any 4-passenger vehicle beyond 100 MPH starts requiring pretty serious power) So you need 9 hours of fuel. 60 gallon capacity, you could burn no more than 6.6 gallons per hour. Well, you can make about 90 horsepower with 6.6 gallons of fuel per hour. That thing is not going to be airborne on 90 horsepower (remember -- no lifting surfaces) much less fly 900 miles.

9) Enough. You get my point? I have seen a lot of these "miracle aircraft" come and go over the decades, and the main thing they have in common is for one reason or another they never quite come into existance.

So, I've heartlessly trashed submarines and aircars... what's next? How about ornithopters, or maybe lighter-than-air vehicles?

tanstaafl.


"There Ain't No Such Thing As A Free Lunch"

MK2 that is...

Frank van Gestel

wasn't there a Simpsons episode on this?

____________________
Murray 06000047

exotic unobtainium alloys

I laughed out loud when I read that.

there are a lot of numbers that don't add up here.

I read through your numbers, and I see your point. I was skeptical of the aircar, too, when I first read about it, but I didn't have any numbers to base my skepticism on. I wonder if anyone has pointed out this particular Emporer's nakedness to its investors?

One thing, though:

Since the aiframe lacks wings or other lifting surfaces, the lift/drag ratio is going to be ridiculous.

I was under the impression that it would be a sort of a lifting-body design. That at full forward thrust, there would be a decent amount of lift generated by the whole thing. I'm no aerospace engineer, though, so I don't know.

--Tony smacks his forehead--

D'oh! I've just encouraged Doug's number-crunching again. Bad! Bad!

___________
Tony Fabris

that leaves 50 pounds for each 120 HP engine, which is about 1/3 the weight per horsepower of any internal combustion engine I am aware of

Then you haven't seen the twin rotor Norton rotary engines they are using. They powered motorbikes for quite a while, with an overall weight of 35 lbs for the race engines. I can't remember the specific BHP figures, but they were generating the same shaft outputs (and higher) than 1,000 cc bikes, whilst being officially rated as 600cc capacity. A damn good engine design.

that the engines are Wankel-type rotary engines. These engines have never been known for fuel economy

They are Norton rotaries. Norton specifically marketed the engine for lightweight, airborne applications, including drone engines and unmanned surveilance aircraft. They have excellent fuel economy and low weight - the road bikes they powered regularly returned around 34-40 mpg even when you thrashed the knackers off them. They only really got thirsty at low RPM, and the race bikes eventually sorted this out by good engine management and new fuelling strategies.

65 decibels at 500 feet. Yeah, right. With eight engines cranking out 960 horsepower and four eight-bladed ducted fans screaming for all they're worth...

Don't forget ducted fans are inherently quieter outside the duct - I think they are referring to the dBA (perceived loudness) levels on the ground.

So, I've heartlessly trashed submarines and aircars... what's next?

...and a good laugh was enjoyed by all. For someone who professes to be "no engineer", you do a pretty damn good job of analysis... Nice one, Doug!

PS. Oh, they may have one other minor problem that you don't mention here - Norton Motors (1974) Ltd. went belly up due to fraudulent financial dealing and bad marketing about 6 years ago - they don't make the engines any more and didn't license their manufacture to anyone....

PPS How did we get to be talking about rotary engines when we started out about AR screens?


One of the few remaining Mk1 owners... #00015